1. Field of the Invention
The present invention relates to a magnetic head carriage assembly for use in a disc drive device for driving a floppy disc or the like.
2. Description of the Prior Art
As the density of the information written on a magnetic recording disc increases, an important problem has arisen in disc drive device, with regard to stabilizing head touch the contact between a recording head and a floppy disc. Another problem that has arisen concerns decreasing the spacing loss so as to obtain stabilized recording or reproducing signals of the magnetic recording disc.
The magnetic discs used for the magnetic disc drive device are usually produced by punching an original magnetic sheet which is wound in a roll, therefore the produced magnetic discs tend to be curled. The magnetic discs are enclosed in a disc cartridge case. When the disc cartridge containing such a curled magnetic disc is driven in the disc drive device, the magnetic disc is rotated with the peripheral portion of the disc fluttering vertically relative to the rotation plane of the disc, whereby the magnetic head contact with the magnetic disc is apt to be unstable.
In order to suppress the fluttering of the magnetic disc and to assure a good contact between the magnetic head of the disc drive and the magnetic disc, there has been employed a magnetic head carriage assembly as shown in FIG. 1. The conventional magnetic head carriage assembly 1 comprises a head carriage 3 carrying a magnetic head 2 and a clamper 7 carrying another magnetic head 5 or a pad 6 which faces to the magnetic head 2 and biased toward the head carriage 3 by means of a resilient plate 4. A magnetic disc 8 is rotatably clamped between the two magnetic heads 2 and 5 or the magnetic head 2 and the pad 6.
The magnetic head carriage assembly using the pad 6 is employed in the disc drive device for a one sided magnetic disc. To the contrary, the magnetic disc using the magnetic head 5 is employed in the disc drive device for a dual sided magnetic disc.
In the magnetic head carriage assembly for the one sided magnetic disc, conventionally the magnetic head 2 is secured on the head carriage 3 in such a manner that the magnetic head 2 is embeded in a slider 9 having a width greater than the width of the core of the magnetic head 2. The slider 9 is supported on a base 10 secured to the head carriage 3. The magnetic disc 8 is clamped between the top flat surface of the slider 9 the level of which is flush with the magnetic head 2 and the pad 6 made of molding of natural fibers or synthetic fibers having a suitable resiliency so that a magnetic gap of the magnetic head 2 can be contacted onto the recording surface of the magnetic disc 8. The bottom surface of the pad 6 has substantially the same flat shape of the top surface of the slider 9.
In the magnetic head carriage assembly for the dual sided magnetic disc, as shown in FIG. 3, the magnetic heads 2 and 5 are respectively embeded in the sliders 12 and 13 each having a width greater than the width of the magnetic head and being supported on gimbal spring assemblies 14 and 15 so as that the magnetic head 2 faces the slider 13 and the magnetic head 5 faces the slider 12. By clamping the magnetic disc 8 by the sliders 12 and 13, the magnetic disc 8 can be contacted to the magnetic gaps of the magnetic heads 2 and 5.
In the conventional magnetic head carriage assembly mentioned as above, fluttering of the magnetic disc can be suppressed to an extent by clamping the magnetic disc between two magnetic heads 2 and 5 or the magnetic head 2 and the pad 6. Also even if an angle of approach of the magnetic disc 8 to the magnetic head is changed, the magnetic head can follow the magnetic disc by resiliently supporting magnetic head by the gimbal springs 11, 14 and 15.
However, since the clamping force of the head carriage 3 and clamper 7 is set at about a few tons of grams to prevent undesired wearing of the magnetic head, in the case wherein the amount of curl of the magnetic disc is great, the force applied by the magnetic disc to the magnetic head is greater than the clamping force of the head carriage, so that the clamper jumps upward.
In the conventional magnetic head carriage assembly, the magnetic heads 2 and 5 are so arranged that the movement of the magnetic head in the vertical direction is confined. Thus when the clamper 7 jumps as mentioned above, the magnetic heads 2 and 5 can not follow the magnetic disc 8, thereby causing the magnetic heads 2 and 5 to be disengaged from the magnetic disc 8, resulting in drop out of signals or reduction of the output voltage.
This drawback mentioned above may be eliminated by mounting the magnetic heads 2 and 5 to be movable in the vertical direction on relative to the head carriage 3 and clamper 7. However, in the case wherein the magnetic heads 2 and 5 embeded in the sliders 9, 12 and 13 are mounted on the head carriage 3 and clamper 7, it is difficult to prevent the fluttering of the magnetic disc 8. In addition a great inertial force acts on the assembly of the magnetic heads 2 and 5 and the sliders 9, 12 and 13, and the magnetic heads 2 and 5 follow the magnetic disc 8 with difficulty, thereby causing the head touch to be unstable.
In the case wherein the magnetic heads are solely mounted on the clamper and head carriage without using the slider, the contacting area of the magnetic head with the magnetic disc may be remarkably decreased and the pressing force per unit area of the magnetic head onto the magnetic disc may be undesirably increased, thereby increasing the possibility of injuring the magnetic disc. If the force of supporting the magnetic head is decreased in order to avoid these problems, fluttering of the magnetic disc can not sufficiently be suppressed, thereby causing the head touch to be unstable.